Process plants, like those used in chemical, petroleum or other processes, typically include one or more centralized or decentralized process controllers communicatively coupled to at least one host or operator workstation and to one or more process control and instrumentation devices, such as field devices, via analog, digital or combined analog/digital buses. Field devices, which may be, for example valves, valve positioners, switches, transmitters, and sensors (e.g., temperature, pressure and flow rate sensors), perform functions within the process such as opening or closing valves and measuring process parameters. While a typical process plant has many process control and instrumentation devices, such as valves, transmitters, sensors, etc. connected to one or more process controllers which execute software that controls these devices during the operation of the process, there are many other supporting devices which are also necessary for or related to process operation.
Still further, many process plants have other computers associated therewith which execute applications related to business functions or maintenance functions. Many process plants, and especially those which use smart field devices, use asset management applications to help monitor, track, and maintain the devices within the plant regardless of whether these devices are process control and instrumentation devices or are other types of devices. For example, an Asset Management Solutions (AMS) application sold by Fisher-Rosemount Systems, Inc. enables communication with and stores data pertaining to field devices to ascertain and track the operating state of various field devices. An example of such a system is disclosed in U.S. Pat. No. 5,960,214 entitled “Integrated Communication Network for use in a Field Device Management System.”
Maintenance personnel who are primarily responsible for ensuring that the actual equipment within the process is operating efficiently and for repairing and replacing malfunctioning equipment, use tools such as maintenance interfaces, the AMS application discussed above, and many other diagnostic tools which provide information about operating states of the devices within the process. To maintain information about various field devices in a process control system, the AMS application maintains a database of information about a number of devices. Generally, various devices used in a process control system can be expected to be manufactured by a number of different manufacturers. It is quite likely that not all of the devices communicate with each other or with the process control devices in the same manner. To overcome the problem of incompatibility among devices manufactured by different manufacturers, the process instrumentation industry uses a standardized digital device communications protocol as defined by a foundation such as the HART Foundation, or the Fieldbus Foundation in order to allow a single application to communicate with multiple device types. Typically, these foundations will have a standard that defines how each device identifies itself to a process control system using a standard communication protocol and a device description (DD), where the DD defines the protocol's application layer and various user interface definitions necessary to communicate with the device. Each device type would typically have its own DD, which is a formal description of the data and operating procedures for a field device, including variables, methods, commands, menus and display formats associated with the device. Information about every accessible variable of the device is included in the DD. Such variables include, for example, process measurements, any derived values, and all the internal parameters such as range, sensor type, choice of linearization, materials of construction, etc.
When the AMS application is implemented in a process plant that uses such a device, the maintenance personal responsible for maintaining up to date device related information may need to get help information about various parameters used to describe such a device. System designers using the AMS software, the 375 Communicator or the HART communicator may use a DD to gain further information about a device. As per the FOUNDATION Fieldbus' or the HART Communication Foundation's DD Language, all HART devices have the option to include DD help text to explain each parameter, method, etc., defined for a specific device. Such DD help text can be displayed on applications such as 275 HART Communicator, AMS, etc. However, not all device manufacturers provide DD help for all parameters, and if they do, this help information is generally not very descriptive. Moreover, DD help provided by a device manufacturer is limited to text information only, i.e., it does not include images, sound, etc.